Cremation Urrn

I am making an urn to hold the cremains (ashes) of a client's husband. Shape and size has been determined as well as the glaze. Client wants the ashes to be "hermetically" sealed. As you know, when glazing, the two pieces would be fired not touching and probably having rims of both the urn and the top with no glaze where they would fit together

Question: If I hand dipped each piece as well as the inside rim of the urn but not where the ashes would rest, then poured the ashes in the urn, placed the two pieces together (remember, no resist being used), and fired it so the urn itself and the top would fuse together into one - Would the whole thing blow up at some point because of built up pressure during firing? If it didn't blow up at that point, could the vessel have a higher than normal pressure when it cools down and therefore be more prone to fracture or blow up later? Lastly, after researching the cremation process I discovered the temperature used to render a human body to ashes is about 1650 F. I use cone 6 when firing, about 2355 F. What would happen to the ashes? Remain the same, coalesce into a lump, melt?

I have made urns for people and animals
I suggest sealing the lid with silicone seal after the ashes are in fired pot. Its waterproof and seals very well.
As far as over firing ashes its a bad idea as they will melt at some point and loose the ash quality.
Mark

Sadly, I spent yesterday making an urn for a friends little dog. For two months there were reports of sightings of this sweet dog along a 2 mile stretch. We were so sure she would be reunited until a kayaker found her. As it turns out, she probably was never really sighted. Closure, although it is welcomed, came in such an unexpected manner.

it is sunny and warm here so there was a good chance for it to dry somewhat even though I had to form all parts while they were more wet than I normally do (hand built) . I even made a backup in terra cotta just in case I couldn't get two firings in before they went to pick up the ashes. Planned a slow bisque, hit Start and pop! The fuse on the controller burst. Replacing the fuse was not the issue-- why it burst was the question. Thank goodness I got a quick response from the kiln company and it was only a loose wire. I just started the firing and even though I will be up very late tonight, I want this to go right.

Thanks for the touching, feel good replys but can anyone out there actually answer the questions with certainty in the original post in regards to pressure and explosion possibilities and the condition of the ashes after being exposed to the high temps of glazing? I've considered the silicon and epoxy options.

Thanks for the touching, feel good replys but can anyone out there actually answer the questions with certainty in the original post in regards to pressure and explosion possibilities and the condition of the ashes after being exposed to the high temps of glazing? I've considered the silicon and epoxy options.

The deal is nobody here has fired human ashes to 2355 as you noted(cone 6 is around 2250)-I will say that they will flux out at that temp and be a glob of fired glaze like stuff that is ugly and rough.As to your firing a sealed vessel question that also is a bad idea-put a pinhole size pinhole in unglazed bottom part to relieve pressure as you would not want this to crackwhich is most likely what it can do. I have fired a pot that ran all around the lid and its fine still 20 years later but cracking can occur. So if cracking is ok go for it. If fluxed out ashes are ok go for it.Maybe a better idea is make the glaze from the ashes and fire that-that can also work well.One other point is to test a small vessel and fire some ash in it also as a test. Then tell us the answers.That way we will all know.Mark

ibwalk;
I am pretty sure that you will get a lava like, cruddy mess. That is the direct answer to your question. I have made several cremation urns, including one for my own mother. The jar was 5 pounds of clay with an overhead lid with knob. The jar is glazed on the inside as well as the outside.After it comes out of the glaze firing. the ashes are placed within and the lid is sealed with Epoxy on both surfaces. Because this jar is buried, I always make two. One is kept by the family.
If you seal the jar and fire it in the kiln without an air hole, you have a good chance of it blowing up.
Tom.[TJR].

I am finishing an urn for my son-in-law's ashes and will ship it to my daughter to finish her arrangements. In talking with the funeral home, she was told that after the cremains are put in the urn, it would be sealed with a wax. The reason behind this is that often times people want to scatter the ashes at a later date (but keep the urn as a momento of a life well lived), or later, be joined with their partner's ashes after they have passed.

In my opinion, the urn should be finished and turned over to the client for final decisions.

lbwalk, reading this thread through, it seems to me that you were in an anxious state. Had I realized this initially, I would not have added my post. Two things though--First, the thread title is about cremation urns in general. Secondly, Mark and Neil had already answered your concern.

Very interesting information on this thread, thank you. I am designing an urn for my father's ashes but am not sure what volume I should allow for nor how best to work out the dimensions of the form to accommodate this (the maths for ellipsoid volume calculations gets too complex for me!).
Can anybody advise me please? I have in mind a very simple, roughly egg-shape urn in a clay (Oxidising St Thomas from Potclays, UK) that will be earthenware fired.
Thank you in advance.
Chris

When I made an urn, the funeral home was happy to put the ashes into the urn and seal it. There is no way I would take responsibility for the ashes, much less put them into my kiln where so much could go wrong.

For what it's worth, I did put small lugs on the urn and got some nice cord to sort of macramé the lid to the urn.

Very interesting information on this thread, thank you. I am designing an urn for my father's ashes but am not sure what volume I should allow for nor how best to work out the dimensions of the form to accommodate this (the maths for ellipsoid volume calculations gets too complex for me!).Can anybody advise me please? I have in mind a very simple, roughly egg-shape urn in a clay (Oxidising St Thomas from Potclays, UK) that will be earthenware fired.Thank you in advance.Chris

As stated by Diane, one cubic inch per pound of body weight is the formula for figuring urn space. The math beyond that, is up to you. Don't forget to carry the one.....

I like the idea of making two matching vessels. I may have to start doing that.

I had made the urn but was concerned it might be too small. To figure volume, I filled the urn with water, measured the water, and then used calculations available online to determine volume in cubic inches. Measuring pieces you already have can give you some idea of the size needed.